Get to Know the New M-E Pavement Design Guide

An ongoing series of Federal Highway Administration (FHWA) workshops is introducing State pavement design, traffic, and materials engineers and others across the country to the new Mechanistic-Empirical (M-E) Pavement Design Guide and its accompanying software. Developed under National Cooperative Highway Research Program (NCHRP) Project 1-37A, the guide provides a uniform basis for the design of flexible, rigid, and composite pavements, using M-E approaches that more realistically characterize inservice pavements and improve the reliability of designs.

The new guide was developed as a tool to support and eventually replace the 1993 American Association of State Highway and Transportation Officials Guide for Design of Pavement Structures, which was based on empirical equations derived from the road test conducted by the then American Association of State Highway Officials between 1958 and 1960. The road test used a limited number of pavement sections at one location, with traffic levels far below those of today.

The guide provides a uniform basis for the design of flexible, rigid, and composite pavements, using M-E approaches that more realistically characterize inservice pavements.

A primary benefit of the new guide is that it uses M-E numerical models to analyze input data for traffic, climate, materials, and other factors and to then estimate damage accumulation over the pavement's service life. Analysis can be done on designs for new, reconstructed, and rehabilitated pavements.

The new guide uses mechanistic-empirical numerical models to analyze designs for new, reconstructed, and rehabilitated pavements.

In 2003, FHWA created a Design Guide Implementation Team (DGIT) to focus on supporting implementation efforts by States and industry through technology transfer and development. The team is currently presenting the Climatic Inputs for M-E Pavement Design workshop, which aims to familiarize participants with modeling climatic effects on pavement performance using the design guide, reducing climatic effects through materials selection and design, and analyzing current State design methods for climatic effects. The free 1-day workshop includes discussions of the Enhanced Integrated Climatic Model used in the design guide, environmental effects on material properties, and pavement performance. Also featured is a demonstration of the M-E design guide software. The target audience includes State materials, pavement design, and geotechnical engineers and industry or academic consultants involved in pavement design. The workshop has been presented in seven States this year, with four more sessions scheduled for August and September.

New M-E Pavement Design Lead States Group

A new Lead States Group is providing guidance and support to the implementation of the M-E Pavement Design Guide. The group, which includes representatives from 19 States and liaisons from FHWA and NCHRP, was established through FHWA to promote and facilitate the refinement, implementation, and evolution of M-E pavement design procedures. The Lead States Group will develop a model implementation plan, share information and lessons learned, identify gaps in the knowledge base and new research needs, and serve as a resource to other States, among other activities. Current group initiatives include developing technical briefs that will highlight different aspects of the design guide such as the guide's climatic models and its use of Long Term Pavement Performance program data. For more information on the Lead States Group, including a list of contact names for each Lead State, visit www.fhwa.dot.gov/pavement/dgit/leadstates/index.cfm.

"The workshops have been very successful, with an average of 30 attendees at each session and usually at least 3 States represented. There is a lot of interest in learning about implementation of the new design system," says Leslie Myers of FHWA's Office of Pavement Technology. For those unable to attend a workshop, the September 19 session in Rocky Hill, Connecticut, will be Webcast live over the Internet at www.ct.gov/dot/fhwa-webcast. "Viewers can submit questions during the Webcast, and they will be answered by FHWA DGIT team members in real time," says Myers.

"Sharing the information through the Webcast will allow many other States to participate and learn more about the design guide," says Donald Larsen, Transportation Supervising Engineer for the Connecticut Department of Transportation's (ConnDOT) Division of Research. The Webcast will be recorded and will then become available online for on-demand viewing a few months after the workshop. ConnDOT previously hosted Webcasts of an August 2004 FHWA workshop that provided a general introduction to the design guide and a March 2005 workshop on materials-related input needs for using the design guide. In addition to the 30 onsite participants for each workshop in Rocky Hill, Connecticut, FHWA estimates that the previous Webcasts reached approximately 1,000 people at over 100 locations, including participants from Canada, China, the United Kingdom, South America, and Australia.

FHWA's Office of Asset Management and the DGIT will host a one-time workshop this fall on the Use of Pavement Management System Data to Calibrate M-E Pavement Design. "This workshop is intended to help pavement design engineers and pavement management engineers better understand how data from pavement management systems can be incorporated in the new Mechanistic-Empirical Pavement Design Guide software," says Myers. The workshop will be held September 20, 2006, in Rocky Hill, Connecticut, and will also be Webcast simultaneously.

Another workshop that will be presented and Webcast in 2006 is Traffic Inputs for M-E Pavement Design Guide. The workshop will share best practices, identify concerns, and develop solutions for the traffic data collection required for successful use of the M-E design guide. ConnDOT will host the workshop and conduct a simultaneous Webcast in Rocky Hill, Connecticut, on September 18, 2006.

For more information on the M-E design guide workshops or to register for a workshop or Webcast, visit www.fhwa.dot.gov/pavement/dgit/index.cfm. Information is also available from FHWA's Design Guide Implementation Team.

Upcoming M-E Pavement Design Guide Workshops

Climatic Inputs for M-E Pavement Design

August 1, 2006, Fayetteville, AR

August 15, 2006, Phoenix, AZ

September 6, 2006, Minneapolis, MN

September 19, 2006, Rocky Hill, CT

Use of Pavement Management System Data to Calibrate M-E Pavement Design